Leecher (computing)

In the context of peer-to-peer (P2P) file sharing networks, a "leecher" refers to a user who downloads files from other users (peers) without simultaneously uploading (sharing) those files or other files back to the network, or who uploads at a significantly lower rate than they download. The term carries a negative connotation within P2P communities.

A leecher's behavior negatively impacts the health and efficiency of the P2P network. The network relies on users contributing bandwidth and storage capacity to share the files they have downloaded, allowing others to access them. When many users leech, the swarm (the group of peers sharing a particular file) can become unstable, leading to slower download speeds for everyone, including the leechers themselves.

Various P2P protocols and communities have implemented mechanisms to discourage leeching. These mechanisms may include ratio-based systems (where users must maintain a certain upload-to-download ratio to continue downloading), karma systems (where users earn points for uploading and lose points for downloading), or outright banning from the network. The effectiveness of these measures varies depending on the specific network and its user base.

The term "leecher" can also be used more broadly in online contexts to describe someone who benefits from a community or resource without contributing back in a meaningful way.